Signaling system



{ F. ZOGBAUM SIGNALING SYSTEM Filed Nov. 24, 1923 June 14, 1927.

Patented June 14, 1927.

UNITED STATE PATENT OFFICE.

FERDINAND ZOGBAUM, OF NEW YORK, N. Y., ASSIGNOR T WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y, A CORPORATION OF NEW YORK.

SIGNALING SYSTEM. 7 l

Application filed November 24, 1923, Serial No. 676,843.

This invention relates to signaling systerns and particularly tosignaling systems for use in connection with the remote control andsupervision of power switches and the like.

It is an object of the invention to provide an improved signalingsystem, whereby switches or other devices may be remotely controlled andsupervised. i The invention provides a central or controlling stationand a plurality of remote stations joined by a normally closed lineconductor. Distributors are provided at the central station and each ofthe remote sta- 5 t-ions, and are adapted to be operated in synchronismwhen set in motion by mechanisms controlled at the central station.v A

plurality of power switches areprovided at each of the remote stationsand are adapted to be operated by individual control keys at the centralstation through the mediiim of the synchonously operated distributors.Certain of the contacts on the distributors at the remote stations areconnected to auxiliary contacts on the power switches and are includedin circuits adapted for the transmission of answer-back signals to thecentral station upon the operation of the respective power switches.

In accordance with a feature of the invention, the distributor actuatingmechanisms are normally disconnected from the line circuit and areadapted to be simultaneously associated therewith preparatory to thetransmission of the distributor controlling impulses.

According to anotherfeature of the invention. means is provided foroperating the distributors in accordance with controlling impulsestransmitted from the central station whereby the distributors, insteadof being operated by a definite predetermined order or number ofimpulses, are operated by such of the impulses as are determined by thedistributor controlling mechanisms. More specifically, after thedistributor actuatin; mechanisms have been associated with the linecircuit andthe impulse transmitting device has been set in operation,the first impulse transmitted will operate the distributor actuatingmechanisms to advance the distributors one step, and each succeedingimpulse transmitted over the line will advance the distributors only ifthe distributor actuating mechanisms have had time to the system is atrest.

According to another feature of the inven-- tion, means is provided forlooking out such istinctive answer-back signals during the transmiss'onof controlling impulses. 7

Othereatures and advantages of the invention will appear from thefollowing description and the annexed drawing which illustratesdiagrammatically one embodiment of the invention. 7

Referring to the drawing, a central station A and a plurality of remotestations B and C are connected by means of a common line conductor 1. Aplurality of power switches 2 and 2 are located at each Of .tl18 remotestations, but, for the sake of clearness, only the power switches at thestation B are shown.- These switches are adapted to control theapplication of current from a power line comprising conductors 4 and '5to oads 6 and 6, respectively, according to whether the power'switchesare opened or closed. Thepower switches 2. and 2' are adapted to becontrolled from the central station A and are also adapted to beoperated automatically by local means responsive to H abnormalconditions on the power line. The power switch 2 is controlled by meansof a polarized relay 8 and thepowerswitch 2 is controlled by means of apolarized relay 8', these relays being operated from the central stationA in a manner hereinafter to be described. Under the conditions shown inthe drawing, the power switch 2 is energized over a circuit extendingfrom grounded bat- 10 0 tery 10, through winding of power switch 2,conductor 11, contact 12 of underload relay 13, contact 14 of overloadrelay 15, contact 16 and armature of polarized relay 8 to ground.Thepower switch 2 thus being closed, current is supplied to the load 6over a circuit extending from conductor 5 of the power line, throughcontacts 17 and 18 of the power switch, load 6, windin of underloadrelay 13 winding of over oad relay to conductor 4 of the power line. Ifnow, the polarized relay 8 is'energized by current of. negativepolarity, it will be 8V1- dent that the circuit of thepower switch willbe broken at the contact16 and that the power switch will be deenergizedand open the energizing circuit of the load 6 at the contacts 17 and 18.l urthermore, even it the polarized relay 8 is maintained in the closedposition shown in the drawing nevertheless the power switch 2 will bedeenergized upon the occurrence of an overload or under-load on thepower line. For example,

if the current on the power line should'fall,

below the minimum required to maintain the under-load relay 13 operatedthe armature of this relay will fall back and open the energizingcircuit of the power switch 2 at the contact 12. As soon as the powerswitch 2 is opened an auxiliary contact 20 controlled thereby is alsoopened, thus deenergizing a slow releasing or time operated relay 19.

The time required for the relay 19 to become fully djeenergized may beadjusted in accordance with the nature of thevload 6. If the load 6 bean ordinary lighting circuit the relay 19 may be adjusted to close itscontact 21 in 10 or 20 seconds to again operate the power switch 2 inorder that the lighting circuit comprising the load may not be cut-offfrom the power line for too long a. time, but if the load 6 be in thenature of -motors employed to run mills or factories,

the relay 19 would preferably be so adjusted as to require thirtyseconds to one and onehalf minutes for closing theconta-ct 21 in orderthat all such motors might attain a state of rest before again beingconnected to the power-line. As soon as the relay 19 in deenergizingcloses its contact 21, an energizing circuit for the power switch2 iscompleted from grounded battery 10, through winding of power switch 2,conductor 11, armature and contact 21 of relay 19, contact 14 ofoverload 15, contact 16 and armature of polarized relay 8 to ground,thus again closing the power switch. If, however, the abnormal conditionreferred to still exists on the power line, thec power switchwill beagain deenergized'in the manner described and a minute or twolater,depending upon the adjustment of relay 19, will again beenergized, whichopening and closing of the power switch transmits a distinc-v tivesignal to the central station A in a manner hereinafter to be described.The attendant at the central station, observing that the power switch 2is being opened and closed. may operate the polarized relay 8 at stationB thereby opening the energized circuit of the power switch 2 at thecontact 16 and preventing the further opening and closing of the powerswitch until the'troulole on the power line is repaired. If a suddensurge of current is impressed upon the power line the power switch 2will be opened due to the When the overload condition is removed,

contact 14 is made manually. The power switch 2 is provided withcontrolling elemeats-identical with those describcdin connection withpower switch 2, similar elenicnts bearing the same reference numeralswith primes aflixed thereto. Summarizing, the above, the power switchesat the remote stations are adapted to be operated selectively by meanscontrolled at the central station A and are also adapted to becontrolled automatically by local apparatus individual to each powerswitch upon the 00- currence of an'overload or underload on the powerline; and furthermore, when any power switch is operated a circuit willbe completed for transmitting an answer-back signal to the centralstation and, if the system be at rest when such operation takes place, v

spectively, while additional control switches 122 and 123 are allottedto the control of similar switches at station (l. Upon the operation ofany power switch an apswerback circuit is prepared for operating asignal controlling relay at the central station of which polarizedrelays 24 and 25, allotted respectivel to power switches 2 and 2, are

typical. olarized relay 24 controls a pair of lamps 26 and 27 forindicating the position of the power switch 2, while polarized relay 25controls a pair of lamps 28 and 29 for indicating the position of powerswitch 2. One or the other of each of these pairs of lamps is normallylighted, current being supplied thereto from a grounded battery 30,through contacts controlled by the armatures of relays 24 and 25. In theposition shown .in the drawing, the lamp 26 is lighted over a circuitextending from grounded battery 30, through filament of lamp 26,contact. 31 v and armature of relay 24 to ground; while the'lamp 29 islighted over a circuit extending from grounded battery 30, throughfilament of lamp 29, contact 32 and armature of polarized relay 25 toground. Upon the operation of the polarized relay 24 by current ofnegative polarity, however, the lamp 26 is extinguished and lamp 27 islighted over a circuit extending from grounded bat ,tery- 30, throughfilament of lamp 27, contact 33 and armature of polarize relay 24 toground; while upon the operation of polarized relay 25 by current ofpositive polarity the lamp 29 is extinguished and lamp 28 is lightedover a circuit extending from grounded battery 30, through filament oflamp 28, "contact 34 and armature of polarized relay 25 to ground.

The power switch controlling relays 8 and 8' at the remote stations andthe signal controlling relays 24 and 25 at the central station are,controlled through the medium ofsynchronously operated distributorswitches 35 and 36 which are preferably of the type disclosed in PatentNo. 1,472,465 to O. F. Forsberg and R. M. De Vignier, dated ()0- tober30, 1923. These distributors are each provided with two brush arms, thedistributor 35 being provided with arms 37 and 38 and the distributor 36with arms 39 and 40, similar elements being provided at' station C. Thecontact arm 37 of distributor 35 is adapted for selective engagementwith an arcuate row of contacts, half of which are alloted to thecontrolkeys 120 121, etc, and the other half of which are allotted to thesignal controlling relays such as 24 and 25. At the remote Station B andall other similar remote stations, such as station C, the brush arm 39of distributor 36 is adapted for selective engagement with an arcuaterow of contacts, one half of which are allotted to power switchcontrolling relays, such as 8 and 8 and the other half of which areconnected to auxiliary contacts on the various power switches for thepurpose of transmitting an answer-back signal to the central stationupon the operatiori'bf the power switches. At all of the stations, thelower contact bank of the distributors contains a single contact whichis normally engaged by the lower brush arm,such as arm 38 or 40, butwhich is opened when the distributor takes its first step, and issubsequently closed when the distributor has made one completerevolution to. stop the rotation of the brush arm.

The apparatus of the system is normally at rest and functions only whenthe power switches are operated from the central station or'whenautomatic operation is taking place at the various remote stations. Ifthe despatcher at the central station A wishes to operate a particularpower switch at one of the remote stations, he operates the appropriatecontrol key at the central station and then starts the distributorcontrolling mechanisms which cause all of the selectors to step up andsearch out each one of their respective contacts. When the distributorsat the central station and a given substation reach the contacts whichare allotted, respectively, to the operated control key and the owerswitch to be operated, a circuit will be completed which includes thecommon line conductor 1 for operating the desired power switch, andsubsequently upon the further advancement oi the distributors, ananswer-back circuit will be completed through the medium of these samedistributors for controlling the appropriate lamps at the centralstation.

The above features together with other important features of theinvention will ap-" pear more clearly from the following description ofthe operation of thesysteng: As pointed out above, when the attenda ntat the central station A desires to open or close any power-switch atany of the remote stations, he operates the appropriate control key andthen starts the distributor controlling mechanisms, causing thedistributor at the central station as'well as the distributors at allthe remote stations to stepup and search out each of their respectivecontacts. If, for example, it is desired to open the power switch 2 atstation B, the control switch 120 is moved into engagement with itslower contact 41, thus connecting current of negative polarity fromgrounded battery 42 to the contact 43 of distributor 35. A key 44, whichis preferably of the two-position typey biased to make contact at 45when arm 44 is unrestrained is then moved, opening the contact 45 andclosing the contact 46. This operation of key 44 deenergizesa slowreleasing relay 47 and energizes a slow releasing relay 48, over obviouscircuits, causing relay 48 to attract its armature and disconnect thesource of current of positive polarity 49 from the line circuit andallowing the armature of slow releasing relay 47 to fall back andconnect current of negative polarity from battery 50 to the lineconductor 1. During the interval between the opening of the line by therelay 48 and the subsequent closing of the line by the release of thearma- 105 ture of relay 47, line .relays 51 and 52 at the central andremote stations respectively are deenergized. The armature of relay 5lin falling back closes contact 53 thus completing an energizing circuitfor a slow releas- 11 -ing relay. 54 which extends from grounded battery55, through winding of relay 54, conductor 56, contact 57 and armatureof a two winding relay 58, contact 53 and armature of line relay 51, toground. A similar-circuit is completed at the station B, as well as allother remote stations, which may be traced from grounded battery 59,through winding of slow releasing relay 60, conductor 61, contact 62 andarmature of relay 63, contact 64 and armature of line relay 52 toground. The energization of slow releasing relay 54 closes its contact65, thus short circuiting the line relay 51 out of the line 1, Y andalso closes-a contact 66 thereby associating the brush arm 37 of theselector 35 with the line 1 for signaling purposes, as willhereinafterappear. Similarly, the operation of slow releasing relay 60 shortc'i'rcuits the line relay 52 through contact 67 and also closes acontact 68 adapted for signaling purposes.

As soon as the slow releasing relay 47 at the central station A haspermitted its armature to fall back to connect current of negativepolarity to the line 1, as described above, a polarized relay 69 at thecentral station is thereupon energized with current of negative polarityover a circuit extending from grounded battery 50, through armature andcontact of relay 47 contact 70 of impulse wheel 71, conductor 72, brusharm 38 and contact 74 of distributor 35, windings of polarized relay 69to ground Relay 69 is the two-position type locking in the position towhich it is last operated. A similar polarized relay 73 at the remotestation B is also energized with current of negative polarity overacircuit extending from grounded battery 50, through armature and contactof relay 47, contact 70 of impulse wheel 71, contact 65 of slowreleasing relay 54, line conductor 1,

4 over a circuit extending from grounded bat- 3o conductor 75, brush arm40 and contact 76, of distributor 36, windings of polarized relay 7 3 toground. The operation of the polarized relay 69 by current of negativepolarity closes contact 7 7. thus, energizing the stepping magnet '78 ofthe distributor 35 tery 79, through armature and contact 77 of polarizedrelay 69, winding of stepping magnet 78, contact 57 and armature ofrelay 58, contact 53 and armature of line relay 51 to ground. Similarly,the operation of the olarized relay 73 at the remote station B ycurrent'ofnegative polarity completes an energizing circuit for thestepping magnet 80 of the distributor 36 which extends from of relay 63,contact 64 and armature of re-- lay 52 to ground. The stepping magnet 78of distributor 35 in energizing attracts its armature thus opening thecontact 84 which is in the energizing circuitof relay 58. The relay 58in deenergizing opens contacts 57 and 86, the former of which is in theenergizing circuits of magnet 78 and slow releasing relay 54. The magnet78 thus being deenergized allows its armature to fall back, advancingthe distributor 35one step, and also permitting the closing of contact84. The slow releasing relay 54 in opening its contact 65 removes theshort circuit from the line relay 51; A similar operation takes place atstation B and all other remote stations.

The key 44 at central station A may now be released, opening contact 46and closing contact 45, but since the relays 47 and 48 are of the slowreleasing type there will be a short time interval between theapplications of negative and positive currents to the line conductor 1,in order that the distime enough to take one step ahead. The

distributors'atall stations have-now taken one step .ahead. The vimpulsewheel 71, which is provided with a plurality of teeth in excess of thenumber of contacts on the upper row of the distributors is now rotatedto 0 en and close the line conductor 1 periodically at the contact Thisimpulse wheel is arranged to make one revolution and stop and is offthetype disclosed in Patent- 1 .354,814 to, J. C. Field dated October 5,1920, but any similar type of impulse wheel may be used. The periodicopening and closing of the line conductor 1 alternately (leenergizes andenergizes line relays 51 and 52. The deenergization of line relay 5Lcloses its contact 53 thus completing energizing circuits for thestepping mag, net 78 and the slow releasing relay 54 as described above.The stepping magnet 78 in attracting its armature opens the contact.

84, as described above, thus deenergizing relay 58 which was previouslyenergized over a circuit extending from grounded battery 85,.throughWinding of relay 58, armature and contact 86 of relay 58, contact 84 ofstepping magnet 78 to ground. The de- .also furtheropens its ownenergizing circuit'at the contact 86. The slow releasing relay 54 indeenergizing opens its contacts 65 and 66, thus again connecting theline relay 51 to'the line conductor 1 where it will again be deenergizedby the next opening of the line circuit. However, since the relay 54 isof the slow releasing type it will not release its armatures until theselectors have had suilicient time to advance one step. When the contact65 of the relay 54 is opened the line relay 51 will again be energizedthus completing an energizing circuit for the relay 58 which extendsfrom grounded battery 85, through winding of relay 58, contact 109 andarmature of relay 51 to ground. The distributor actuating mechanismswill thus be returned to their normal positions at the completion ofeach advance of the distributors. Since the distributor 36 is steppedforward in exactly the same manner as the distributor 35, when the brusharms of these distributors arrive upon corresponding contacts a circuitwill" brush arm 39 of distributor 36 will arrive upon the contact 88 anda circuit will be completed from grounded battery '42,

I through contact 41 of control key 120, con-.

tact 43 and brush arm 37 of selector ..conductor 89, contact 66 andarmature of slow releasing relay 54, line conductor 1, contact 67 andfront armature of slow releasing relay 60, back armature andcontact 68of relay 60, conductor 90, brush arm 39 and contact 88 of selector 36,windings of polarized relay 8 to ground. Since the polarized relay 8 isthereupon energized by current of negative polarity its armature will beattracted to open the contact 16,

thus deenergizing the power switch 2 in the manner described above. Eachsucceeding step of the distributors is accomplished in the same mannerso that the brush arms will be stepped around in synchronism passingcorresponding contacts of each distributor at the same time.

When the power switch 2 is closed, as shown in the drawing, itsauxiliary contact 91 is also closed thereby connecting current ofpositive polarity from the battery 92 to the contact 93 of thedistributor 36,

but when this power switch is opened by the operator as described above,the auxiliary contact 91 will be associated with a battery 94 ofnegative-potential and thus when the v brush arm 39 of selector 36arrives upon contact 93, andi the brush arm 37 of distributor 35 arrivesupon the corresponding 9 contact 95, the polarized lamp controllingrelay 24 at the central station A will be energized by current ofnegative polarity over a circuit extending from grounded battery 94,through auxiliary contact 91 of power switch 2, conductor 96, contact 93and brush arm 39 of selector 36, conductor 90, contact 68 and backarmature of slow releasing rela 60, front armature and contact 67 of reay 60, line conductor 1, back armature and contact 66 of slow releasingrelay 54, conductor 89, bush arm 37 and contact 95 of selector 35,windings of polarized relay 24 to ground. In operating, the relay 24opens contact 31 and closes contact 33, thus extinguishing lamp 26 andlighting lamp 27 in the manner described above. After the brush arms ofdistributors 35 and 36 have made one revolution, the lower brush arms 38and 40 will engage'conta'cts 74 and 76, respectively. As soon as thisoccurs the polarized relay 69 is energized by current of positivepolarity over a circuit extending from grounded battery 49, througharmature and contact of slow releasing relay 48, contact 70 of impulsewheel 71, conductor 72, brush arm 38 and contact 74 of distributor 35,windings of polarized relay 69 to ground. The relay 69, being energizedby current of positive polarity attracts its armature toopen the contact77, thus opening the operating circuit of the stepping magnet 78 andthereby stopping the rotationof the brush arms of the distributor 35. Atthe same time the polarized relay 73 at remote station B and all otherremotestations is also energized by current of positive polarity,thereby opening the circuit of the stepping magnet 80 at contact 82 andstopping the rotation of the brush arms of selector 36.

The impulse wheel 71 is provided with more teeth than are necessary fora complete revolution of the distributor since the opening of the lineby some of the teeth may have no effect on the line relays 51 and 52,such a condition sometimes existing when these line relays remain shortcircuited longer than usual due to the slow release of the armatures ofrelays 54 and 60 respectively. Furthermore, should one of thedistributors lose a step and lag behind the others, it will continue tobe stepped forward to the correcting position by the extra impulse untilit catches up with the other rected or synchronized once in'everyrevolution.

A special answer-back signal is provided for not fying the attendant atthe central station A when any outlying power switch operates due toabnormal conditions when the system is at rest. This signal comprises aspecial pilot lamp 100, which may be of some distinctive size or color,and which is normally lighted when the system is at rest but which isextinguished upon the operation of any power switch. The extinguishmentof the pilot lamp 100 is accompanied, if desired, by the ringing of abell 101 to give an audible indication of such operation.

Thelamp 100 is normally lighted over a circuit extending from groundedbattery 102/, through armature and contact 103 of a normally energizedrelay 104, filament of lamp 100 to ground. The relay 104 is normallyenergized over a circuit extending from grounded battery 105, throughwinding of relay 104, contact 106 and armature of relay 104, contact 109and armature of line relay 51 to ground. If now, the power switch 2 isdeenergized automatically due say to the operation of the overload relay15, the line 0011- ductor 1 will be momentarily opened in the followingmanner: A relay 110, provided at the remote station E, a similarrelaybeing provided at all other remote stations, is'nor-,

mally short circuited through auxiliary contacts 111, on the powerswitches 2 and auxiliary-contacts 112 on power switch 2, and resistance200 but when the power switch 2 is opened the upper auxiliary'contact111 is likewise opened and the lower auxiliary con-' tact 112 is closed,a similar operation taking place upon the operation of the power switch2. However, during the intei val between 113 of'polarized relay 73,winding of relay 110, to ground, thus attracting its armature andopening the line at the contact 114.

- well as a visible indication of the operation I 114 opened suchcontrol impulse or answer When the line is thus momentarily opened theline relay 51 is momentarily deenergized thus/allowing its armature tofall back and open the contact 109 thereby opening the energiz'ingcircuit of the relay 104 which thereupon allows its armatures to fallback and open. the contacts 103 and 106. The opening of contact 103extinguishes the lamp 100, and the closure of contact 115 ener izes thebell 101 over a circuit extending romgrounded battery 102, through frontarmature and contact 115 of relay 104, winding ofbell 101 to ground,thus giving the attendant at the central station an audible as of thepower switch.

When a power switch at an of the outlying stations opens or closes ue toabnormal conditions onthe power line during the selecting operationdescribed above, the return indication of this operation will be lockedout so that there will be no interference in the system while it is inoperation. This is accomplished at each of the remote stations such asstation B, by the polarized relay 73 whose armature mustbe in engage-'ment with contact 82 during the selecting operation in or er to operatethestepping magnet 80, as de cribed above, and therefore the contact 113must be broken during such selecting operation and thus prevents themomentary ener ization of the relay 110, which, according y cannot openthe line 1. If this were not so it would result either in suchindication being lost or if station 0 were receiving a control impulseor sending an answer back signal at the instant contact back signalwould be lost. When, however, the lamp 100 is extin uished and the bell101 rings at a time w en the system is at rest, the attendant at thecentral station, knowing. that a power switch has operated at one of theremote stations, will operate the key 44 and then set the impulse wheel71 into operation in order to determine which power switch has operated.The distributors at the central station and at the remote stations willthen advance in the marinerpreviously described, their upper brush armseration the relay 104 may again be energized over an obvious circuit byclosing a normally open key 116, thereby again lighting the lamp 100andcutting out the bell 101. It is understood that after any operationinvolving deenergization of relay 104, key 116 must be operated to againenergize this relay.

While the invention has been shown and described in connection with thecontroland supervision of power switches, it is to be understood thatit-is equally applicable to the control and supervision of other devicesor a paratus. Furthermore, since many other 0 anges may be made in thesystem herein shown and described without departing from the spirit ofthe invention, it 1s to be understood that the invention is not limitedin any way except as defined by the scope of the appended claims. v

\Vhat is claimed is:

1. A signaling system comprising-a central station and a remote station,a circuit connecting said stations, a distributor'at each of saidstations, an operating magnet for.

each of said distributors included in a circuit normally open attwo-points, a polarized relay at each station, means whereby thepolarized relays are controlled from the central station to close theassociated operating magnet circuit at one point, a line relay in saidfirst circuit ateach station to close the operating magnet circuit atthe other point, and impulse transmitting means associated with saidcircuit at said central station for operating said line relays.

2. A signaling system comprising a central station and a remote station,a normally closed circuit connecting said stations, a distributor ateach of said-stations, an operating magnet for each of said distributorsin a circuit normally open at two points, a polarized relay at 'eachstation, means whereby the polarizedrelays are controlled,

from the central station to close the associated operating magnetcircuit at one point, a normally energized relay in said first circuitat each station to close the associated operating magnet circuit at theother point, and means at said central station for periodically openinand closing said circuit to alternately eenergize and energize saidnorma lly energized relays.

-3. A signaling system comprising a central station and a remotestation, a normally closed circuit connecting said station, a normallyenergized line relay in said circuit at each of said stations, adistributor simultaneously passing over and searching at eachof saidstations, an operati g magout corresponding contacts and in turnoperating the appropriate indicating relays 24 and 25 at the centralstation A, thus extinguishing one of the lamps associated therewith and1i hting another to indicate which power switc has operated. After thisopnet for each of said distributors controlled by the normally ener izedrelay thereat, means controlled at sai central station for preparing theoperation of said distributpr ma ets, means at said central station forperiodically opening and closing said normally closed circuit too cratesaid line relays, a slow releasing re ay at each station operated uponthe deenergization of the line relay thereat, means controlled by saidslow releasing relays for shunting the re-' tral station and a remotestation, a circuit connecting said stations, a distributor at each ofsaid stations,'an operating magnet for each of saidfdistributorsincluded in a circuit normally open at two points, apolarized relay ateach station, means whereby the polarized relays are controlled from thecentral station to close the associated distributor circuit at onepoint, a line relay in said first. circuit at each station to close theoperating magnet circuit at the other point, impulse transmitting meansassociated with said circuit at said central station for operating saidline relays, and means controlledby the operating magnet at each Istation and operative when said distributor ated stepping distributorsat said stations,

normally at rest, devices at said remote station, means whereby saiddevices are controlled from said central station over said circuitthrough the medium of said distributors, a signal at said centralstation, means whereby the signal is operated when'said distributors areoperating, automatic means at sa d remote station for operatln SELlddevices, and means associated wlth t e circuit for operating said signalwhen the distributors are at rest and the devices are operatedautomatically. 1

, 6, A signaling system comprising a central station and a plurality ofremote stations, synchronously operated stepping distributors at saidstations normally 'at rest, a circuit connecting said stations, devicesat said remote stations, keys at said central station, means whereby thekeys selectively operate said devices over said circuit through themedium of said distributors, means for operating said distributors,pairs of signaling lamps at said central station corresponding toxthedevices at said remote stations, circuits including means controlled bysaid devices over said circuit to light one of the signaling lampsof'corresponding pairs through the medium of said distributors,automatic means for operating said devices, a signal distinct from saidsignaling lamps, means whereby the signal is operated when saiddistributors are operating,

and means associated with the circuit for FERDINAND ZOGBAUM.

21 day of November A. D.,

